动态组合SQL语句方式实现批量更新的实例

using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Text;
using System.Data.SqlClient;

public partial class Index : System.Web.UI.Page
{
    SqlConnection sqlcon;
    string strCon = ConfigurationManager.AppSettings["conStr"];
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.GV_DataBind();
        }

    }
    public void GV_DataBind()
    {
        string sqlstr = "select * from tb_inf";
        sqlcon = new SqlConnection(strCon);
        SqlDataAdapter da = new SqlDataAdapter(sqlstr, sqlcon);
        DataSet ds = new DataSet();
        sqlcon.Open();
        da.Fill(ds, "tb_inf");
        sqlcon.Close();
        this.GridView1.DataSource = ds;
        this.GridView1.DataKeyNames = new string[] { "id" };
        this.GridView1.DataBind();
        if (GridView1.Rows.Count > 0)
        {
            return;//有数据，不要处理
        }
        else//显示表头并显示没有数据的提示信息
        {
            StrHelper.GridViewHeader(GridView1);
        }
    }
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            string gIntro = e.Row.Cells[4].Text;
            e.Row.Cells[4].Text = StrHelper.GetFirstString(gIntro, 12);
        }
    }
    protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
    {
        string id = this.GridView1.DataKeys[e.NewSelectedIndex].Value.ToString();